Prosecutors and the FBI have repeatedly interviewed the billionaire in question, Mar-a-Lago member Anthony Pratt, and he was the one who spilled the beans on Trump. Pratt claimed that during a conversation with Trump, he mentioned the American submarine fleet. The ex-president then got excited, leaned closer to be stealthy, and told him two crucial pieces of information about U.S. submarines:
1) The exact number of nuclear warheads they carry.
2) Exactly how close they can get to a Russian submarine without detection.
This information would be EXTREMELY useful to America's adversaries and is something Trump should never have revealed. Pratt then went on to share the information with at least 45 other people via emails and conversations.